Create transactions.c

Author: tr3sp4ss3rexe

transactions.c

@@ -0,0 +1,62 @@
+/*
+Handles simple transactions and avoids race conditions 
+with the help of mutexes when interacting with critical regions
+*/
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+double bankAccountBalance = 0;
+bool lock = 1;
+
+void deposit(double amount) {
+    pthread_mutex_lock(&lock);
+    bankAccountBalance += amount;
+    pthread_mutex_unlock(&lock);
+}
+
+void withdraw(double amount) {
+    pthread_mutex_lock(&lock);
+    bankAccountBalance -= amount;
+    pthread_mutex_unlock(&lock);
+}
+
+unsigned odd(unsigned long num) {
+    return num % 2;
+}
+
+void do1000Transactions(unsigned long id) {
+    for (int i = 0; i < 1000; i++) {
+        if (odd(id))
+            deposit(100.00);
+        else
+            withdraw(100.00);
+    }
+}
+
+void* child(void* buf) {
+    unsigned long childID = (unsigned long)buf;
+    do1000Transactions(childID);
+    return NULL;    
+}
+
+int main(int argc, char** argv) {
+    pthread_t *children;
+    unsigned long id = 0;
+    unsigned long nThreads = 0;
+    if (argc > 1)
+        nThreads = atoi(argv[1]);
+    children = malloc( nThreads * sizeof(pthread_t) );
+    for (id = 1; id < nThreads; id++)
+        pthread_create(&(children[id-1]), NULL, child, (void*)id);
+    do1000Transactions(0); // main thread work (id=0)
+    for (id = 1; id < nThreads; id++)
+        pthread_join(children[id-1], NULL);
+    printf("\nThe final account balance with %lu threads is $%.2f.\n\n", nThreads, bankAccountBalance);
+    free(children);
+    pthread_mutex_destroy(&lock);
+    return 0;
+}